• 2d materials
• ballistic transport
• bjt
• contact resistance
• effective Hamiltonian
• graphene
• hbt
• heterostructure
• modeling
• mos2
• spin
• tlm
• transistor
• transmission line model
• twisted bilayer graphene
• wse2

Understanding ballistic transport is fundamental for next generation electronics, thus computational modeling is essential for designing future devices. This thesis walks three steps in this direction. First, the introduction of a new device concept: an heterojunction bipolar transistor made of 2D materials. This device is the thinnest transistor concept possible, and we present its proof-of-concept and its figures of merit. Second, we present the Vertically-Ballistic Transmission Line Model, a new multiscale model describing transport across a bilayer structure used as a vertical contact. This model is tuned on few experimental parameters such as mobilities and dopings, and it gives numerous insights on the physics of a van der Waals vertical contact. Lastly, we simulate vertical spin transport in twisted bilayer graphene to look for effects useful for designing spintronic devices.